The pusher furnaces are designed for continuous operation, and push plates around a rectangular work pattern through the furnace. The pusher furnace is guided by a two phase work cycle:
The plates are pushed along a stainless steel rack on the front of the furnace. At this time, the processed product is removed, and new product is added.
The product is pushed toward the back of the machine and inserted into the queue for the main pusher. Once in line with the main pusher, the product is pushed into the furnace. The product is then pushed back to the front tray where it can be unloaded.
Various models of pusher furnace are available based on size and pushing speed. The systems are designed to support adjustable push rates as well as adjustable temperatures. The motion system is completely computer controlled via various micro-stepping motors and controllers dependent on furnace size. The push rates range from 0.1" up to 5.0" per minute and can be adjusted further through gear reducers. Temperature is computer controlled by the ADAPT System.
The furnace is comprised of a double-walled shell of 1/8" thick sheet metal and 1/4" thick endplates, separated by an air space to facilitate lead cooling and provide a cooler exterior. The entire furnace assembly, including the insulation construction, are machined using CNC devices to ensure repeatability and accuracy. The pusher furnace heating elements have been specially selected and designed to ensure that they never exceed the manufacturer's recommended watt density. Even during heat-up, there are no restrictions to how much power is supplied. While the furnace is idling at temperature, it is running well below the manufacturer's recommendations for watt density. This, coupled with the design distance from the other elements, the chamber wall, and the work charge, ensures a long life for the heating element.
The insulation is energy efficient and consists of brick and ceramic fiber insulation. Other designs rely on a thin insulation wall to cut costs, and while the initial investment is reduced using this method, the furnace life suffers as thermal stresses on the insulation pack cause a breakdown in the furnace lining. Unlike thin-walled designs, a Mellen pusher furnace lining should never need replacement.
Temperature sensors are available in multiple lengths and temperature ranges.
Custom ceramics are available in virtually any shape required - simply provide a CAD file, drawing, or description.
The over temperature alarm helps protect against overheating of the furnace.